I think that this restriction is good, though. For other uses, there are other file formats (Gemini protocol supports the use of other file formats too, e.g. you can use audio/ogg or audio/opus for audio, image/png or image/xpixmap for pictures, etc; a client might not support them and a user might not want them, so really you should use text if that is suitable (I am one who would rather have an explanation in text rather than a video), although you can still have links to other files too if needed) and other protocol (e.g. NNTP for slow communication (including if you want to allow comments for your articles), IRC for fast communication, Telnet/SSH for interactive applications, and other protocol should be made up for database access then you can use a SQLite extension to access them) (the text/gemini format can include links to other protocols too).